THESIS
2016
xv, 71 pages : illustrations (some color) ; 30 cm
Abstract
During chlorine disinfection of drinking water, halogenated disinfection byproducts (DBPs)
are generated from the reactions among natural organic matter, inorganic ions and chlorine.
Recently, aromatic halogenated DBPs have raised increasing public concern, due to their
significantly higher toxicity than aliphatic halogenated DBPs. In this study, with ultra
performance liquid chromatography/electrospray ionization-triple quadrupole mass
spectrometry (UPLC/ESI-tqMS), three new aromatic halogenated DBPs were confirmed in a
12-h simulated chlorinated drinking water sample, including
tetrabromo-4-hydroxy-acetophenone, dibromo-4-hydroxy-acetophenone, and 3-bromo-5-formylsalicylic acid. Besides, it was found that when DBPs were separated using the UPLC
with gradient eluent, their rete...[
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During chlorine disinfection of drinking water, halogenated disinfection byproducts (DBPs)
are generated from the reactions among natural organic matter, inorganic ions and chlorine.
Recently, aromatic halogenated DBPs have raised increasing public concern, due to their
significantly higher toxicity than aliphatic halogenated DBPs. In this study, with ultra
performance liquid chromatography/electrospray ionization-triple quadrupole mass
spectrometry (UPLC/ESI-tqMS), three new aromatic halogenated DBPs were confirmed in a
12-h simulated chlorinated drinking water sample, including
tetrabromo-4-hydroxy-acetophenone, dibromo-4-hydroxy-acetophenone, and 3-bromo-5-formylsalicylic acid. Besides, it was found that when DBPs were separated using the UPLC
with gradient eluent, their retention times (RTs) had a direct relation with their structures:
aliphatic DBPs were eluted before aromatic ones, and DBPs with longer RTs tended to be
more toxic. Moreover, a new method was developed to separate aliphatic and aromatic DBPs
using UPLC based on their RT ranges (with RT 2.5 min as the dividing line). With this method, the DBPs in simulated chlorinated drinking water samples with different contact
times from 0.5 to 72 h were separated into aliphatic and aromatic fractions. The total organic
halogen (TOX) and developmental toxicity were examined for both fractions of each water
sample. The results showed that in the first 12 h, the TOX of the aromatic fraction was higher
than that of the aliphatic fraction, and after 12 h, the TOX of the aliphatic fraction became
higher than that in the aromatic fraction. However, for the samples with short contact times (<
2 h), the toxicity of the aromatic fraction (with higher TOX concentration) was lower than
that of the aliphatic fraction. To explain this, UPLC/ESI-tqMS analyses were conducted for
each sample, and several groups of intermediate DBPs with RTs on the boundary of aliphatic
and aromatic DBPs were discovered. These intermediate DBPs might form at short contact
times and present high toxicity, and thus need to be further studied.
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